1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor device and, more specifically, to a method of manufacturing a semiconductor device capable of preventing loss of dopants due to external diffusion thereof from a junction area, by forming a cobalt mono-silicide film through a first RTP process, implanting carbon ions not serving as a donor or an acceptor with a low energy and a low dose to make the film amorphous, and then forming a cobalt silicide film through a second RTP process.
2. Discussion of Related Art
Generally, in a logic device, a cobalt silicide film is formed on source/drain regions (active regions), in order to decrease a contact resistance between a unit transistor formed in a lower portion of the device and an upper metal interconnection. As a result, operation speed of the device is enhanced due to improvement of an RC delay characteristic of the device. Only by forming the cobalt silicide film on the source/drain regions (active regions), an ohmic contact is formed in a contact portion between a tungsten plug and the cobalt silicide film, thereby decreasing a contact resistance thereof.
On the other hand, a concentration of dopants in a junction area formed by performing a high concentration n-type or p-type ion implanting process has a large influence on the contact resistance. Here, in case of a high concentration p-type junction area, while the cobalt silicide film is formed in the junction area in which dopants, etc. are distributed in a constant concentration, the cobalt silicide film makes inroads into the concentration distribution formed in the highly-concentrated ion implanting process. On the other hand, ions of BF2 are redistributed due to the subsequent heat budget when or after B and F are separated to form the cobalt silicide film, so that B is externally diffused toward the surface of the cobalt silicide film and F is piled up on an interface between the junction area and the semiconductor substrate. As a result, the roughness of the interface between the junction area and the semiconductor substrate after forming the cobalt silicide film is increased. This causes deterioration of leakage current characteristic in an n-well junction, which is important for characteristics of a device actually implemented.